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THRESHOLD-FREE NEURAL NETWORK MODELS FOR DETECTION OF ZEBRAFISH LARVAE BOUTS FROM TAIL ANGLE KINEMATICS
No full textZebrafish larvae are a powerful model for studying sensorimotor processing, often utilizing the optomotor response (OMR). Accurately detecting discrete swimming bouts- the fundamental units of zebrafish locomotion- from kinematic data is crucial for behavioral analysis. However, traditional threshold-based detection methods struggle with noise and variability in bout kinematics. This thesis addresses the need for robust, threshold-free bout detection by developing and evaluating deep learning models based on tail angle kinematics. We present two convolutional neural network (CNN)-based models: an offline CNN-LSTM model for post-processing analysis and a streamlined online CNN model for real-time applications. These models were trained and validated using tail tracking data acquired from head-fixed larval zebrafish subjected to OMR stimuli via a novel, integrated Stytra+PsychoPy closed-loop workflow, which overcomes stimulus refresh rate limitations of default setups. Both models achieved high performance without relying on pre-defined thresholds; the offline model yielded mean precision/recall of 83.15%/89.83%, while the online model demonstrated viability for real-time use with minimal performance decrease (mean precision/recall 84.09%/87.14%), albeit with measurable latency. We validated our experimental setup by showing that bout kinematics in head-fixed fish under closed-loop conditions were largely comparable to free-swimming behavior, supporting the biological relevance of the training data. Furthermore, we applied the offline model to compare OMR kinematics across wild-type (WT) AB, Nacre, and Casper strains. While Nacre and Casper exhibited similar kinematics, both differed significantly from WT AB, particularly in bout duration under closed-loop conditions and in adaptation dynamics during closed-loop/open-loop transitions. These findings highlight the effectiveness of threshold-free deep learning models for zebrafish bout detection and underscore the importance of considering strain-specific behavioral differences in sensorimotor research
Intermediate-Temperature Membrane-less H₂/O₂ Fuel Cells
No full textHydrogen fuel cells are promising candidates for clean and efficient energy conversion in transportation and stationary applications. However, conventional proton exchange membrane fuel cells (PEMFCs) rely on polymer membranes such as Nafion™, which suffer from high cost, strict water management requirements, and thermal instability above 80 °C. In this work, we develop and evaluate a membraneless hydrogen-oxygen fuel cell system designed to operate under elevated temperatures (up to 120 °C) using a liquid electrolyte interposer. The cell employs two porous Pt/C electrodes and a circulating acid or alkaline electrolyte to conduct ions without a solid membrane. Room-temperature tests show superior performance in acidic media compared to alkaline, and Intermediate-Temperature testing reveals stable open-circuit voltage and enhanced power output due to accelerated reaction kinetics. Our results demonstrate that a simplified, thermally tolerant membraneless architecture can reduce system complexity while maintaining performance, providing a viable path toward next-generation hydrogen fuel cells
DIET QUALITY DURING PREGNANCY IN RURAL INDIA: EXAMINING INFLUENCE OF SOCIO-DEMOGRAPHIC FACTORS AND ASSOCIATION WITH MATERNAL NUTRITION AND NEWBORN OUTCOMES
No full textBackground and objectives:
Adequate nutrition during pregnancy is critical for maternal and newborn health but remains understudied in low-resource settings. The Global Diet Quality Score (GDQS) offers a novel metric to assess diet quality in such contexts. This dissertation utilized data from an Alive & Thrive (A&T) maternal nutrition trial in rural Uttar Pradesh, India, to examine diet quality and influencing factors from early to late pregnancy and evaluate associations with nutrient adequacy and maternal and birth outcomes.
Methods:
Data were from the A&T trial (2017–2019), comprising survey data from two cross-sectional samples (n=1,341) and a longitudinal sample (n=475) of pregnant women, with the latter including repeated multi-pass 24-hour dietary recalls in early and late pregnancy. The GDQS was derived from 25 food groups (range 0–49), and the mean probability of adequacy (MPA) for 11 micronutrients was computed using dietary data. Survey data included gestational weight gain, hemoglobin, mid-upper arm circumference (MUAC), birth weight, and gestational age at birth. Descriptive analyses examined changes in diet quality and nutrient adequacy, and multivariable regression analysis identified factors associated with GDQS and its association with nutrient adequacy and maternal and newborn outcomes.
Results:
Diet quality was consistently poor, with mean GDQS ~17–18, improving by only 0.6 points between early and late pregnancy. Micronutrient adequacy was also low (MPA 13% to 16%), and GDQS was positively correlated with nutrient intakes and adequacy. Women with more antenatal care visits, higher nutrition knowledge, and higher socioeconomic status had higher GDQS, highlighting inequities in diet quality. GDQS was not significantly associated with gestational weight gain, hemoglobin, or MUAC, but each unit increase in GDQS was associated with 0.03 kg greater birth weight (95% CI: 0.01, 0.05) and 0.17 weeks longer gestation (95% CI: 0.04, 0.31).
Conclusions:
Maternal diet quality remained consistently poor with minimal improvement during pregnancy, indicating that women in this rural Indian context may fail to meet increased nutritional requirements. Higher GDQS was correlated with micronutrient adequacy and associated with improved birth but not maternal nutrition outcomes. Future research is recommended to validate GDQS in diverse pregnant populations
Psychometric Evaluation of brightwheel’s Experience Assessment
Full text linkThe purpose of this psychometric evaluation was to assess the validity and reliability of
brightwheel’s Experience Assessment. The assessment was designed to be used by
early learning center educators to obtain a comprehensive and multidimensional view of
a child’s learning journey across eight domains of development. The primary focus of
this report is on the evidence for the assessment’s reliability and validity as
demonstrated by indicators of domain score distributions, internal consistency reliability,
measurement invariance, and item-test correlations.
● The present study used a purposive sample of 593 students 0-5 years of age in
10 early learning centers across eight U.S. states.
● Trained educators used the assessment to rate students, collecting data during a
5-week period in the spring of 2025.
● The assessment measure consisted of eight domains divided into 73 sub-skills.
On each sub-skill, students could be rated from benchmark 1 (infants) to 8
(primary grades).
● Results showed that domain score distributions were generally normally
distributed and moved in the expected direction across student ages (i.e., higher
scores for older children), suggesting that the assessment produces scores that
align with the developmental progress expected.
● Sub-skills within each domain were highly inter-correlated. For all domains,
Cronbach’s alpha was >.90, indicating excellent internal consistency reliability
and providing evidence that sub-skills within a domain measure the same
underlying concept.
● Internal consistency patterns were sustained when comparing subgroups of
students in centers that used brightwheel’s broader Experience Curriculum to
students in centers that did not, as well as when disaggregated by curriculum
product lines (i.e., Preschool, Toddler, Baby). The assessment’s similar
performance across groups provided evidence of measurement invariance.
● All individual items were positively and highly (r >.80) correlated with their
respective total domain scores, and thus no items were recommended for
exclusion from the assessment.
● Overall, the findings provided strong evidence regarding the reliability and validity
of the Experience Assessment across all assessment domains and curriculum
product lines, contributing initial support for the assessment as a tool to measure
early learning milestones
THEY SEE OUR MAGIC BUT NOT OUR STRESS: EXAMINING SUSTAINABILITY IN BLACK WOMEN PRINCIPALS
Full text linkAlthough an essential presence in K-12 education, Black women are woefully underrepresented in the scholarship on educational leadership. The existing research shows that Black women’s unique leadership style positively impacts the well-being of the students, staff, and schools they serve. The current literature on Black women principals reveals common themes amongst the experiences of Black women that highlight a unique standpoint. This standpoint provides insight into the needs of Black women in school leadership. To ensure that Black women principals remain in their seats, there must be more insight into how intersectionality affects their ability to achieve work-life balance, build productive relationships, receive stakeholder support, and feel
accomplished. Examining how these factors present in the ecological systems of Black women
principals provides further insight into their ability to sustain as leaders. Using Black feminist
thought theory as a theoretical framework, this study aims to build on the limited body of work
focused on the experiences of Black female principals by centering their leadership experiences,
surfacing their collective knowledge, and identifying and examining the organizational structures
and support that contribute to their sustainability. A secondary purpose of this research is to
investigate how the constructs associated with burnout present in Black women. Creating more
transparency around the leadership experience of Black women by surfacing the factors that lead
to their thriving or not thriving in principalships can positively impact schools and districts
across the nation
Human Agency in Spinoza: A New Analysis
Full text linkIn this dissertation, I freshly reexamine Spinoza’s account of human agency. On a standardly received scholarly narrative which is most elaborately defended by Olli Koistinen, Spinoza maintains that we are more than bystanders to external forces, even though he rejects free will and accepts causal determinism and necessitarianism. I challenge this orthodox interpretation.
I take the following strategy: firstly, I take a cue from some contemporary attempts to articulate what it is for us to be an agent in which the expression ‘helpless bystanders’ is indeed used as what it is to be contrasted with agents. Specifically, I refer to David Velleman’s account of agency and set it as our point of reference for our default ordinary concept of agency in order to solidify what it is for us to be “more than bystanders to external forces”. Secondly, I show that there are textual reasons to believe that Spinoza cannot make room for what is required of agency on Velleman’s account. Thirdly, I show how Spinoza’s moral theory is designed in such a way that it does not require agency in the sense of the capacity to be more than helpless bystanders to external causes. I then lastly critically engage with attempts to defend the standard reading in the literature according to which we are more than bystanders to external forces, for Spinoza.
The outcome of my doctoral research is that, for Spinoza, we are indeed ‘helpless bystanders’ to the forces external to us insofar as we are ‘acted on’ in his sense, whilst we are still ‘helpless bystanders’ to the forces ‘internal’ to our essence, which in turn is determined by God rather than by our deliberation, insofar as we ‘act’ in his sense. In both cases, we are helpless bystanders to God’s determinations through and through
Oral History Interview with Vanessa N. Gamble
No full textThis interview with Vanessa Northington Gamble, MD, PhD, is part of “Moral Histories: Voices and Stories from the Founding Figures of Bioethics,” an oral history project of the Johns Hopkins Berman Institute of Bioethics. Dr. Gamble is University Professor of Medical Humanities at George Washington University and Professor of Health Policy and American Studies. Her areas of expertise include the history and sociology of medicine, the history of race in American medicine, disparities in health care and public health, and Black health and well-being.
Dr. Gamble, a fourth-generation West Philadelphian, describes her family, community, and early education, including the impact of the 16th Street Baptist Church bombing, and the assassination of Martin Luther King, Jr. when she was 15. After graduating from Philadelphia Girls’ High School, she describes her education at Hampshire College where she wrote her senior thesis on the US Public Health Service Syphilis Study. Dr. Gamble recounts her introduction to bioethics as an undergraduate intern at The Hastings Center and her subsequent medical school and graduate student experiences at the University of Pennsylvania where she earned an MD-PhD.
She recalls essential mentors, particularly Dr. Helen Dickens, when she lost both her mother and sister to cancer. During her tenure at the University of Wisconsin-Madison, she recounts her leadership role in securing a presidential apology for the Syphilis Study at Tuskegee, delivered by President Bill Clinton in 1997, which included federal funding for the creation of the National Bioethics Center at Tuskegee University, where she was later director. Dr. Gamble highlights the 2005 conference she convened for Black bioethicists to discuss and propose a Black agenda for bioethics that brought issues of Black health and racial injustices in healthcare to bioethics discussions. She stresses the importance of community engagement and the need to focus on the trustworthiness of institutions, which includes a discussion about vaccine hesitancy in communities of color during the Covid-19 pandemic. The interview concludes with her move to George Washington University, her courses on race and public health, and her evolving work as historian of Black women in medicin
Essays on Heterogeneous Agent Macroeconomics and Unemployment
Full text linkThis dissertation consists of three chapters that study how the microeconomic characteristics of unemployment shape business cycle dynamics and macroeconomic policy.
The first chapter investigates the macroeconomic consequences of a well documented microeconomic fact: Job loss results in a substantial decline in labor earnings that persists for over 20 years. This chapter argues that this `scarring' effect of unemployment is a key determinant of the speed of a macroeconomic recovery following a recession. I incorporate human capital into a heterogeneous agent New Keynesian model with search and matching frictions. Unemployment scarring, mediated by the fraction of temporary versus permanent layoffs, enables the model to capture both the sluggish recovery from the Great Recession and the swift rebound from the COVID Recession. In particular, the presence of scarring reveals the pivotal role that temporary layoffs fulfilled in preventing a sluggish post-pandemic recovery.
Chapter 2 studies how household beliefs about job finding and job loss evolve over the business cycle. Using expectations data from the Survey of Consumer Expectations and real-time machine learning forecasts, we construct rational benchmarks and show that beliefs adjust slowly and vary widely across households. We embed these patterns in a heterogeneous-agent model. Belief stickiness dampens the initial drop in consumption during downturns but slows recovery by limiting households’ ability to draw down savings once conditions improve.
The third chapter evaluates and compares the effectiveness of commonly pursued fiscal stimulus policies during recessions. Using a heterogeneous agent model calibrated to match measured spending dynamics over four years following an income shock, we assess the effectiveness of three fiscal stimulus policies employed during recent recessions. Unemployment insurance (UI) extensions are the clear “bang for the buck” winner when effectiveness is measured in utility terms. Stimulus checks are second best and have two advantages (over UI): they arrive and are spent faster, and they are scalable to any desired size. A temporary (two-year) cut in the rate of wage taxation is considerably less effective than the other policies and has negligible effects in the version of our model without a multiplier
THE BLOOD-BRAIN BARRIER: STRUCTURE, FUNCTION, DEVELOPMENT AND TOXICOLOGICAL CHALLENGES
Full text linkThe blood-brain barrier (BBB) is a critical component in maintaining the brain's microenvironment by selectively permitting the passage of essential nutrients and blocking harmful substances. This literature review explores the structure and function of the BBB, emphasizing its role in drug delivery challenges and chemical toxicity prediction. Key topics include the significance of electrical resistance as a measure of BBB integrity, historical research milestones, and the developmental dynamics of the BBB, particularly the formation of tight junctions and transporter expression. The review assesses various models used in toxicological studies to replicate BBB properties, the impact of barrier disruption on BBB permeability, and strategies for therapeutically opening the BBB to enhance drug delivery. Misconceptions about the BBB, current research gaps, and future directions for improved experimental models are addressed. This synthesis highlights the evolution of BBB research and its implications for neuroscience and pharmacology, offering insights into the BBB's critical role in brain health and disease
Exposed Bodies: Dressing and Undressing Women in Italian Chivalric Literature
Full text link“Exposed Bodies: Dressing and Undressing Women in Italian Chivalric Literature” offers a comparative analysis of Matteo Maria Boiardo’s Orlando innamorato, Ludovico Ariosto’s Orlando furioso, and Torquato Tasso’s Gerusalemme liberata, the three most influential chivalric poems of the Italian Renaissance, by focusing on the relationship between clothing and the gendered bodies they interact with in the
narrative. Specifically, I argue that garments, armor, masks, and even the absence of clothing are not mere descriptive details, but rather powerful and active semiotic signs whose narrative implications evolve as Italian chivalric romance progresses from the fifteenth to the sixteenth century. By analyzing Boiardo, Ariosto, and Tasso’s poems, I demonstrate how the use of these signs enables women to subvert the gendered dynamics of the literary tradition, by manipulating the male gaze that would otherwise constrain their agency within the conventions of the genre. However, these signs are usually wearable and, therefore, impermanent; they can be removed, either deliberately or by force, and this dynamic highlights a fundamental distinction between characters depicted as men from those depicted as women. Men can lose the wearable signs that signify them, but this loss never constitutes a
permanent condition. Conversely, women’s power to shape and control the gaze of others is fleeting, only temporarily granted by clothing, and it shifts to a state of passive nakedness when stripped away. In other words, I argue that while knights are dressed and armored, women are naked and defined by the gaze of others. At the same time, nudity itself can be read not only as an empty medium on which signs are inscribed, but also as an active element of the semiotic dynamics described so far. Therefore, the last section of this dissertation explores instances where nakedness itself functions as a costume for female characters. A tool for seduction or a signifier of vulnerability; either way, a signal that elicits male reactions, both within the narrative worlds of the poems and among their contemporary audience